Circuit breaker



J. G. JACKSON CIRCUIT BREAKER Sept. 15, 1953 Filed Dec. 22, 1951 24 A Z; F 1y 2/ ".1 I

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CIRCUIT BREAKER Filed Dec. 22, 1951 Y 2 Sheets-Sheet 2 HTTOFNE'K Patented Sept. 15, 1953 UNITED STATES OFFICE CIRCUIT BREAKER John G. Jackson, Detroit, Mich., assignor to. Square D Company, Detroit, .Mich.,..a cnllporae tion of Michigan 14 Claims.

This inventionrelates to apparatus for making and breaking electrical circuits and more particularly to circuit breakers automatically operable in response to current overloads and manually operable with a snap action.

An object of the present invention is to provideo an improved form of quick make and quick break automatic electric circuit breaker of simple and economical construction.

A further object of the present invention is to provide an improved form of snap-acting mechanism requiring a, reduced handle movement and, therefore, reduced operating space to efiect the desired snap action.

A further object of the present invention is to provide an improved form of circuit breaker mechanism in which the operating mechanism is pivoted in the side walls of the casing and side cover.

Further objects and features of the invention will be readily apparent to those skilled in the art from the following specifications and appended drawings illustrating certain embodiments of the invention in which:

Figure l is a side view of the circuit breaker with the side cover removed and showing the operating mechanism in the fon position, certain parts being broken away to facilitate the Showing of other parts.

Figure, 2 is a horizontal sectional View of the circuit breaker taken along the lines II'II of Figure 1.

Figure 3 is an enlarged horizontal sectional view taken along the lines III-III of Figure 2.

Figure 4 is a view similar to Figure 1, with the parts illustrated in the off position.

Figure 5 is a view similar to Figure 1, the parts being shown in the t ipped position- The circuit breaker as shown comprises an open sided casing I of molded insulating mate-- rial in which the breaker contactsand operating mechanism are mounted. A cover 2 of insulated material providing additional mountingsurfaces closes the open side of the casing I and is mounted thereon by means of a plurality ofrivets 3. The casing and cover have integral vertical barriers 4 and 5 which form chambers within the interior of the circuit breaker. A conducting strap 6 is provided at one end ledge '1 of the casing -I, and fits into cut-out slots 8 in the casing l and Side cover -2 which hold strap 6 in place. A threaded terminal screw 9 fits, into a threaded holecut Within the conducting strap and provides means for external connection of the breaker into an electrical circuit. Conducting relative thereto.

of a slot 3'4 in the armature 29.

strap 76 extends through the casing and carries at its inner extremity a stationary contact II which is isolated from the adjacent casing and coverby means of an insulating material I12 which forms an arc chamber surrounding the stationary contact. A switching member 13 carrying a movable contactv M on one end and having a latching surface I5 at the opposite end is provided, and has formed therein a notch H which is pivotally mounted on the big-ht of a generally U-shaped member 16. The legs of U-shaped member [6 have outwardly turned extensions I9 which are pivotally mounted'in-cutout portions l8 inthe side casing I and cover 2.

An end ledge 2| is formed by the end of the casing opposite to the end which forms ledge 1. Upon, ledge 2| there is mounted a second conducting strap 22 which is secured in cutout notches 23 in the casing l and-cover 2. The conducting strap 22 extends into the interior of the device, and has a pressed out central portion 24 near its interior end to which is welded an end of a bimetallic member 25. An element 26 is carried in extensions of the cutout portions 23 adjacent-the upperinterior end of portion 24, Elements 26 has a threaded hole therein in which a stud, 21 operates, stud 21 engaging portion 24 to bent it and thereby Change the position of the bimetallic member 25 to effect calibration of the breaker.

The current responsive tripping means of the circuit breaker, which is more fully described in my copending application for Circuit Breaker, Serial Number 776,528 filed September 27, 1947, now U; 5. Patent No. 2,579,673, granted December 25, 1951, comprises a stationary magnetic yoke 28, a magnetic armature 29 and a resilient latching element '31 mounted upon the bimetallic member 25 and movable bodily therewith and The magnetic yoke 28 and the resilient latching element 3i are secured to the bimetallic member 25 as by means of a rivet 32, and the magnetic armature 29 i pivoted on an upper hook portion 33 of element 3| by means The latching element 3| is provided with a latching nose 3!] as shown in Figure 4 and has a flange 35 at its back end which engages the bimetal 25. The yoke 28 is of generally U-shaped cross section as shown in Figure 2 so that the yoke 28 is energized magnetically by'the current flow through the bimetallic member 25. A flexible conductor 36 interconnects the bimetallic member 25 and the switching member 13, each end of conductor '36 being welded to one of these members.

An operating handle 31 has a hub 38 which is pivotally mounted in suitable depressions in the side casing I and cover 2. Handle 31 has an internally extending arm 39 which is provided with a boss 4!. A generally U-shaped operating member 42 having cutout portions at 43 and 44 has legs 46 which are pivoted in the side casing I and cover 2 in slots 45 provided therein, as shown in Figure 3. Member 42 also has a slot 52 therein through which member E3 extends in the open circuit position. The boss M is fitted into the cutout portion 4-3 to move the operating member 42 about its pivotal mounting upon movement of the operating handle 31. A return bent operating spring 41 has its ends secured to spaced, depending legs 48 of the operating member 42, and fits at its return bent portion in a slot 49 in the switching member I3. I

Barrier is provided with a surface at 53 which operates as a limit for movement of the switching member l3 when the circuit breaker is tripped.

The operation of the circuit breaker according to the present invention will now be explained. Referring to Figure l in which the circuit breaker is shown in the contacts engaged, or on, position, the contacts may be manually disengaged by rotation of the handle in in the clockwise direction. Clockwise movement of the handle 31 produces counter-clockwise rotation of the operating member 42 about its pivotal engagement in slots in the casing I and cover 2. This movement carries the extending legs d8 of the operating member 42 downwardly, until the ends of spring attached thereto pass the point of the pivotal engagement between the U-shaped member 55 and cutout portions iii of the casing I and cover 2. Spring 47 is then in a position in which its resiliency causes rotation of the U- shaped member 16, and the switching member I3 therewith, about its pivotal mounting in the casing I and cover 2, to separate rapidly the movable contact M from stationary contact II. It should be noted that if the spring ll should break or if the contacts should freeze, the upper edge of slot 4 3 will engage the spring member it as operating member 42 pivots, and a positive force will be applied to rotate member it toward the open circuit position. Switching member I3 will thereby be moved to open circuit position.

In order to close the circuit through the circuit breaker after manual opening, handle 3? is rotated in a counter-clockwise direction. Operating member 42 thereby is rotated in a clockwise irection by virtue of the boss 4i-slot 43 connection, and the ends of spring 4': connected to the legs of member 62 are moved upwardly. When these ends pass the point of the pivotal engagement of the member to in the cutout portions Ill, the movable contact I4 is returned into engagement with the stationary contact 1 l with a snap action.

Referring again to the position of the circuit breaker element as shown in Figure 1, should an overload occur in the circuit with which the circuit breaker is associated, either a sudden large surge which operates the magnetic armature member as against the latching nose 3%] or a sustained smaller overload which flexes the bi metallic member 25 to carry the latching nose JG to the position where it releases the latching surface [5 of the switching member l3, the'latching surface i 5 of the switching member I3 is then released. and the switching member 13 is rotated into the position shown in Figure 5 about its pivotal engagement in the bight of the U-shaped member to under the developed. by the oper ating spring Upon the occurrence of such an overload, the movable contact 54 is rapidly disengaged from the stationary contact ii to eiiect a snap acting trip release of the circuit breaker. The latched end of the switching memher it, upon the occurrence of an overload in the circuit breaker, travels toward the top of the breaker until it engages ledge '53 of the barrier Operating member is rotated by spring ll to the position of Figure 5, whereby handle 3': moves to an intermediate ipped position. To effect relatching of the circuit br= or mechanism, the operating handle 3'! is rotated to its extreme clockwise position in which rotation the upper surface of slot 52 of the operating member 52 engages the switching member 13 forcing it downwardly until the latching surface passes below the latching nose The device is then again under manual control, the parts being in the position illustrated in Figure 4., which is also the position of the parts after the circuit breaker has been manually turned off.

The circuit breaker mechanism of the present invention provides the features of quicl -make and quick-break within a reduced arc of movement of the operating handle as is developed by the knee action operatin mechanism. Furthermore, the device has a minimum number of parts, and is extremely rugged and durable. The de-- vice also provides for opening of the circuit therethrough despite a failure of the operating spring or a tending of the contacts to weld together.

While a certain preferred embodiment of the invention has been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

1. An automatic electric circuit breaker having a stationary contact, current responsiv latching means, a switching member having a contact surface at one end cooperating with said stationary contact and a latching surface atits opposite end having a releasable engagement with said latching means, a U-shaped member pivoted on a fixed part and pivotally mounting said switching member, a manual operator, an operating member pivoted at one end on a fixed part and engaging said operator near its opposite end so as to be movable in response to movement of said manual operator, and spring means interconnecting said switching member and said operating member for moving said switching member to open and closed circuit positions in response to movement of said operator. 7 I

2. An automatic electric circuit breaker having a stationary contact, current responsive latching means, a switching member having a contact surface at one end cooperating with said stationary contact and a latching surface at its opposite end having a releasable engagement with said latching means, a U-shaped member pivoted on a fixed part and pivotally mounting said switching member, a manual operator, an operating member pivoted at one end on a fixed part and engaging said operator near its opposite end so as to movable in response to movement or said manual operator, spring means interconnecting said switching member and said' operating member for moving said switching memberto .open and closed circuit 'po'sitions .in response to movement: of said" operator, and means :on said operating member for. applying a positive force to said U-shaped member when said manual. operator is moved to the off positionv whereby. movement of 'said' switching membertotheopen circuit position is effected despite afailure .of; said spring means.

3. An automatic electric circuit breaker having a. stationary contact, current responsive latching means, a switching memberhavinga contact surface at one endcooperating with said stationary. contact and .a latching surface at its opposite end having a releasable engagement with said latching means,.a u-shaped member pivoted on a fixed'part and pivotally mounting said switching member, a manual operator having a pin thereon, an operating member pivotedona. fixed part and having a slot which cooperates with said pin whereby movement of said manual operator eifectsmovement of .said operating member about its pivot, and spring'means interconnecting said switching member and said operating member for moving said switching member to open and closed circuit positions in response to movement of said operator.

4. An automatic electric circuit breaker having a stationary contact, current responsive latching means, a switching member having a contact surface at one end cooperating with said stationary contact and a latching surface at the opposite end having a releasable engagement with said latching means, a U-shaped member pivoted on a fixed part, said switching member having a pivotal engagement with the bight of said U- shaped member, a manual operator, an operating member pivoted at one end on a fixed part and engaging said operator near .its opposite end, and springmeans secured at one end'to said operating members-and at its other end to said switching member for moving said switching member to open and closed circuit positions in: response to movement of said operator, said spring means biasing said U-shaped member into its pivot on said fixed'part and biasing said switching member into its pivotal engagement with said U-shaped member.

5. An automatic electric circuit breaker having a cup-shaped casing and an insulating side cover cooperating therewith, a stationary contact and a current responsive latching means mounted within said side casing'and cover, a switching member having a contact surface at one end cooperating with said stationary contact and a latching surface :at the opposite end having a releasable engagement with said latching means, a U-shaped member pivoted on a fixed partand having a pivotal engagement with said switching member, a manual operator, an operating member pivoted at one end on a fixed part and engaging said operator near its opposite end, said casing and cover having lateral notches'cut therein providing said fixed parts, and spring means interconnecting said switching member and said operating member and providing a bias for mov ing said. switching member about. its pivotal mounting onsaid U-shaped member and for mov ing said U-shaped member about .its pivotal, engagement on said fixed part.

6'. An automatic electric circuit breaker having a cup-shaped casing and an insulating side cover cooperating therewith, a stationary contact and current responsive latching means mounted within said casing and cover, a switching memher havinga contact surface atone end cooperatingrwithrsaid stationary contact. anda latching surface atone end cooperating with said. stationary contact and a. latching surface at the opposite endhaving areleasable engagement with saidilatchinggmeans, a u-shaped member pivoted ona fixed part and having pivotal engagement withsaid switching-member, a manual operator, an operating, member pivoted at one end on a fixed; .partand: engaging said operator near. its opposite end, said side casing and cover having lateral. notches cut therein providing said fixed parts, and spring means interconnecting said switching member and said operating member, said spring, means biasing said contact surface against said stationary contact when. they are engagedv and biasing said switching member for rotation about its pivotal engagement with said U-s'haped member when said latching surfaceis released by said current responsive latching means.

7-. Anautomatic electric circuit breaker having a cup-shaped casing and an insulating side cover cooperating therewith, a stationary contact and current responsive latching means mounted in said casing, a switching member having a contact surface at one end cooperating with said stationary. contact and a latching surface at the opposite end havingv a releasable engagement with said latching means, a U-shaped member pivoted. by the legs thereof in said casing and cover and having a pivotal engagement with said switching member, a manual operator, an operating member, said operating member having a substantially U- shape and having a pivoted engagement at one portion thereof with said side casing and cover and engaging said operator at another portion thereof so as to be movable therewith, and spring means interconnecting said switching member and said operating member .for moving said switching member in response to movement of said manual operator.

8. An automatic electric circuit breaker having a cup-shaped casing and an insulating side cover cooperating therewith, a stationary contact and current responsive latching means mounted in said casing,.a switching member having a contact surface atone end cooperating with said stationary contact. and a latching surface at the opposite end having a releasable engagement withsaid latching means, a generally U-shaped member having one leg thereof pivoted in sai casing and the other leg pivoted in said cover, said switching member having a return bent portion which. is pivotally mounted upon the bight of said U-shaped member, a manual operator having a portion extending within said breaker which carries a pin, an operating member having a slot with which said pin cooperates whereby said operating, member is moved by movement of said manual operator, means pivotally mounting said operating member in said casing and cover, and spring means interconnecting said switching and said operating member for moving said switching member in response to movement of said manual operator.

9. An automatic electric circuit breaker having a cup-shaped casing and an insulating side cover cooperating therewith, a stationary contact and current responsive latching means mounted in said casing, a switching member having accntact surface at one end cooperating with, said stationary contact and a latching sur face. at the opposite end having a releasable engagement with said latching; means, a generally U-shaped member having one leg thereof pivoted in said casing and the other leg pivoted in said cover, said switching member having a return bent portion which is pivotally mounted upon the bight of said U-shaped member, a manual operator having a portion extending within said breaker which carries a pin, an operating member generally U-shaped in cross section, means pivotally mounting said operating member in said casing and cover, said operating member having a slot within which said pin operates whereby operating member is moved upon movement of said manual operator, a pair of legs depending from said operating member, a U-shaped spring, the ends of said spring being mounted to said legs and the bight of said spring engaging said switching member at a point spaced from the pivotal connection of said switching member, rotation of said manual operator effecting movement of said ends of said spring across the point of mounting of said U-shaped member whereby said switching member is moved to open and closed circuit positions.

1G. An automatic electric circuit breaker having a cup-shaped casing and an insulating side cover cooperating therewith, a stationary contact and current responsive latching means mounted. in said casing, a switching member having a contact surface at one end cooperating with said stationary contact and a latching surface at the opposite end having a releasable engagement with said latching means, a generally U-shaped member having one leg thereof pivoted in said casing and the other leg pivoted in said cover, said switching member having a erating member generally U-shapcol in cross section, means pivotally mounting said operating member in said casing and cover, said operating member having a slot within which said pin operates whereby said operating member is moved upon movement of said manual operator, a pair of legs depending from said operating member, a U-shaped spring, the ends of said spring being mounted to said legs and the bight of said spring engaging said switching member at a point spaced from the pivotal connection of said switching member, rotation of said manual operator eifecting movement of said ends of said spring across the point of: mountingof said U-shaped member whereby said switching member is moved to open and closed circuit positions, said switching member pivoting about its engagement with said U-shaped member under the bias of said spring when released by said latching means to move to an open circuit position.

11. An automatic electric circuit breaker having an insulating base, a manual operator, a stationary contact, a switching member carrying a contact surface at one end cooperating with said stationary contact, current responsive latching means for the opposite end of sa d switching member, a U-shaped member having its legs pivotally mounted in said base, said switching member having a return bent portion on an upper surface intermediate its ends pivotally engaging the bight of said U-shaped member, an operating member pivoted in said base and operatively connected to said manual operator whereby movement of said manual operator effects pivotal movement of said operating member, anoperating spring having one portion connected to said operating member and another portion connected to said switching member at a point on the lower surface thereof, movement of said manual operator effecting movement of the line of force of said spring across the point of pivotal mounting of said U-shaped member whereby said switching member is moved to open and closed circuit positions, said switching member pivoting about its engagement with said U-shaped member under the bias of said spring when released by said latching means to move to an open circuit position.

12. An automatic electric circuit breaker having a cup-shaped casing and an insulating side cover cooperating therewith, a stationary contact and current responsive latching means mounted in said casing, a switching member having a contact surface at one end cooperating with said stationary contact and a latching surface at the opposite end having a releasable engagement with said latching means, a generally U-shaped member having one leg thereoi? pivoted in said casing and the other leg pivfoted in said cover, said switching member having a return bent portion which pivotally engages the bight of said U-shaped member, a manual operator having a portion extending within said breaker which carries a pin an operating member generally U-shaped in cross section, means pivotally mounting said operating member in said casing and cover, said operating member having a slot within which said pin operates whereby said operating member is moved upon movement of said manual operator, a pair of legs depending from said operating member, a U-shaped spring, the ends of said spring being mounted to said legs and the bight of said spring engaging said switching member at a point spaced from the pivotal connection of said switching member, rotation of said manual operator effecting movement oi said ends of said spring across the point of mounting of said u-shaped member whereby said switching member is moved to open and closed circuit positions, and means on said operating member for applying a positive force to said U-shaped member when said manual operator is moved to the off position whereby movement of said switching member to the open circuit position is eifected despite a failure of said spring.

13. An automatic electric circuit breaker having a cup-shaped casing and an insulating side cover cooperating therewith, relatively movable contacts and means releasable for effecting relative movement of said contacts, current responsive means normally restraining said releasable means and effecting release upon the occurrence of overcurrent through the circuit breaker, a U-shaped member pivoted in said casing and cover at its legs and pivotally engaging at its bight said releasable means, a manual operator pivoted in said side casing and cover, an operating member pivoted at one end in said side oasing and cover and engaging said operating member near its opposite end, a spring interconnecting said operating member andsaid releasable means, said spring biasing said contacts toward each other in engaged position and away from each other in disengaged position and biasing said releasable means for rotation about said U-shaped member upon release of said releasable means.

14. An automatic electric circuit breaker havmg an open sided casing and an insulating side cover cooperating therewith, relatively movable contacts and means releasable for effecting relative movement of said contacts, current responsive means normally restraining said releasable means and effecting release on the occurrence of overcurrent, a U-shaped member pivoted in said side casing and cover at its legs and pivotally engaging at its bight said releasable means, a manual operator pivoted in said side casing and cover, an operating member pivoted at one end in said side casing and cover and engaging said operating member near its opposite end, a spring interconnecting said operating member and said releasable means, said spring biasing said contacts toward each other in engaged position and 10 away from each other in disengaged position and biasing said releasable means for rotation about said U-shaped member upon release of said releasable means, and means on said operating member for positively efiecting movement of said releasable means to an open circuit position despite failure of said spring.

JOHN G. JACKSON.

References Cited in the file of this patent UNITED STATES PATENTS Number 

